Referring to FIG. 1, a conventional reversible ratchet wrench includes a ratchet head 10, a driving head 20, a pawl 30, a resilient member 40, and a direction-selecting rotary knob 50. The ratchet head 10 includes an annular driving toothed portion 101. The driving head 20 extends through the ratchet head 10, and includes an accommodating space 201 formed in an outer peripheral surface thereof and aligned with the annular driving toothed portion 101. The pawl 30 is disposed in the accommodating space 201, and has a ratchet toothed portion 301 engageable with the annular driving toothed portion 101. The resilient member 40 biases the pawl 30 to engage the annular driving toothed portion 101. The direction-selecting rotary knob 50 is rotatable between first and second positions. When the direction-selecting rotary knob 50 is at the first position, the driving head 20 is limited to rotate in a direction. When the direction-selecting rotary knob 50 is at the second position, the driving head 20 is limited to rotate in an opposite direction. However, since the minimum idle rotation distance of the wrench corresponds to one ratchet tooth, the wrench is not suitable for use in a narrower working space.